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Title: Phosphate Sorption Speciation and Precipitation Mechanisms on Amorphous Aluminum Hydroxide

Abstract

Aluminum (Al) oxides are important adsorbents for phosphate in soils and sediments, and significantly limit Phosphate (P) mobility and bioavailability, but the speciation of surface-adsorbed phosphate on Al oxides remains poorly understood. Here, phosphate sorption speciation on amorphous Al hydroxide (AAH) was determined under pH 3–8 and P concentration of 0.03 mM–15 mM using various spectroscopic approaches, and phosphate precipitation mechanisms were discussed as well. AAH exhibits an extremely high phosphate sorption capacity, increasing from 3.80 mmol/g at pH 7 to 4.63 mmol/g at pH 3. Regardless of reaction pH, with increasing P sorption loading, the sorption mechanism transits from bidentate binuclear (BB) surface complexation with dP-Al of 3.12 Å to surface precipitation of analogous amorphous AlPO4 (AAP), possibly with ternary complexes, such as (≡Al-O) 2-PO 2-Al, as intermediate products. Additionally, the percentage of precipitated phosphate occurring in AAP linearly and positively correlates with P sorption loading. Compared to phosphate reaction with ferrihydrite, phosphate adsorbs and precipitates more readily on AAH due to the higher solubility product (K sp) of AAH. The formation of AAP particles involves Al III release, which is promoted by phosphate adsorption, and its subsequent precipitation with phosphate at AAH surfaces or in the bulk solution.

Authors:
 [1];  [2];  [3];  [4];  [5];  [6];  [5];  [7];  [6]
  1. Huazhong Agricultural Univ., Wuhan (China); Univ. of Wyoming, Laramie, WY (United States)
  2. Stony Brook Univ., NY (United States)
  3. Umeå Univ., Umeå (Sweden)
  4. Canadian Light Sources, Inc., Saskatoon, SK (Canada)
  5. Huazhong Agricultural Univ., Wuhan (China)
  6. Univ. of Wyoming, Laramie, WY (United States)
  7. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS), X-ray Science Division
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
National Science Foundation (NSF); National Natural Science Foundation of China (NNSFC); Swedish Research Council (SRC); USDOE Office of Science (SC)
OSTI Identifier:
1530214
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Accepted Manuscript
Journal Name:
Soil Systems
Additional Journal Information:
Journal Volume: 3; Journal Issue: 1; Journal ID: ISSN 2571-8789
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 54 ENVIRONMENTAL SCIENCES; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Al hydroxide; phosphate; precipitation; sorption; speciation

Citation Formats

Wang, Xiaoming, Phillips, Brian L., Boily, Jean-Francois, Hu, Yongfeng, Hu, Zhen, Yang, Peng, Feng, Xionghan, Xu, Wenqian, and Zhu, Mengqiang. Phosphate Sorption Speciation and Precipitation Mechanisms on Amorphous Aluminum Hydroxide. United States: N. p., 2019. Web. doi:10.3390/soilsystems3010020.
Wang, Xiaoming, Phillips, Brian L., Boily, Jean-Francois, Hu, Yongfeng, Hu, Zhen, Yang, Peng, Feng, Xionghan, Xu, Wenqian, & Zhu, Mengqiang. Phosphate Sorption Speciation and Precipitation Mechanisms on Amorphous Aluminum Hydroxide. United States. doi:10.3390/soilsystems3010020.
Wang, Xiaoming, Phillips, Brian L., Boily, Jean-Francois, Hu, Yongfeng, Hu, Zhen, Yang, Peng, Feng, Xionghan, Xu, Wenqian, and Zhu, Mengqiang. Wed . "Phosphate Sorption Speciation and Precipitation Mechanisms on Amorphous Aluminum Hydroxide". United States. doi:10.3390/soilsystems3010020. https://www.osti.gov/servlets/purl/1530214.
@article{osti_1530214,
title = {Phosphate Sorption Speciation and Precipitation Mechanisms on Amorphous Aluminum Hydroxide},
author = {Wang, Xiaoming and Phillips, Brian L. and Boily, Jean-Francois and Hu, Yongfeng and Hu, Zhen and Yang, Peng and Feng, Xionghan and Xu, Wenqian and Zhu, Mengqiang},
abstractNote = {Aluminum (Al) oxides are important adsorbents for phosphate in soils and sediments, and significantly limit Phosphate (P) mobility and bioavailability, but the speciation of surface-adsorbed phosphate on Al oxides remains poorly understood. Here, phosphate sorption speciation on amorphous Al hydroxide (AAH) was determined under pH 3–8 and P concentration of 0.03 mM–15 mM using various spectroscopic approaches, and phosphate precipitation mechanisms were discussed as well. AAH exhibits an extremely high phosphate sorption capacity, increasing from 3.80 mmol/g at pH 7 to 4.63 mmol/g at pH 3. Regardless of reaction pH, with increasing P sorption loading, the sorption mechanism transits from bidentate binuclear (BB) surface complexation with dP-Al of 3.12 Å to surface precipitation of analogous amorphous AlPO4 (AAP), possibly with ternary complexes, such as (≡Al-O)2-PO2-Al, as intermediate products. Additionally, the percentage of precipitated phosphate occurring in AAP linearly and positively correlates with P sorption loading. Compared to phosphate reaction with ferrihydrite, phosphate adsorbs and precipitates more readily on AAH due to the higher solubility product (Ksp) of AAH. The formation of AAP particles involves AlIII release, which is promoted by phosphate adsorption, and its subsequent precipitation with phosphate at AAH surfaces or in the bulk solution.},
doi = {10.3390/soilsystems3010020},
journal = {Soil Systems},
number = 1,
volume = 3,
place = {United States},
year = {2019},
month = {3}
}

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